Tapering mechanism



Nov. l0, 1925.

F. E. MARTIN,

TAPERING- MECHANI SM Filed may 29. 1924 5 Sheets-Sheet l @not "m Nov. 10, 1925- F. E. MARTIN TAPERING MECHANISM Filed llay 29. 1924 5 Sheets-Sheet 2 aucun.

Nov. 10, 1925.

F. E. MARTIN TAPERING MECHANIS Filed lay 29 1924 v' Sheets-Sheet 5 MMM ' atto/dwg Nov. 10, 1925-` n F. E. MARTIN TAPERING MECHANISM Filed May 29. 1924 5 Sheets-Sheet 5 Patented Nov. 10, 1925.

UNITED STATES PATENT OFFICE.

FREDERICK E. MARTIN, or BERKRLET, CALIFORNIA, AssIeNoR To MARTIN AIR Doe COMPANY, oF sANTRANCIsCo, CALIFoRNIA, A CORPORATION or CALIFORNIA.

Application filed May 29, 1924. Serial No. 7:16344.

To all 'whom it may concern:

Be it known that FREDERICK E. MARTIN,

Y citizen of the United States, residing at Berkeley, in the county of Alameda and State of'California, has invented certain new and useful Improvements in Tapering Mechanism, of which the following is a specification.

This invention relates to improvements in means for tapering logs on sawmill car' riages, and is particularly directed to a motor mechanism having a definite range of t-ravel, made up of a series of independent limited steps, with such motor mechanism arranged in such definite relation tothe knee as to provide for the maximum range of travel without interference with' or by the usual mill equipment. The control of `the motor mechanism is so arranged that the independent steps of motor travel may be successively or selectively controlled to cause the knee tomove for each step in succession throughout the range of travel, or

r for any one of said steps of movement. Furthermore, in the preferred form of the invention, the -motor mechanism is wit-hout direct connection with the knee, and means are provided, whereby the relative initial position of the knee and motor mechanism in so far as the operative contact between these parts is -concerned may be adjusted,

to insure an accurate initial position ofthe knee, thus compensating for wear of the parts.

In my co-pending application, filed November 19, 1923, Serial Number 675,706, ythere is described motor mechanism for tapering a knee, having a definite. range of travel, made up of a series of successive y steps, with the motor having direct connection lwith the knee, means being provided for `operating the motor throughout the series ofstepsin s uceessiom, with each motor. step Idefining a taper position of the knee. In this particular construction, Vthe maximum range of travel ofthe motor, to insure the knee moving from the minimum to the maximum taper position, necessitated such a length of motor that when the motor` wasconnected to the knee, as described in suchapplication, the projection of the motor interfered tosome extent with certain necessary mill equipment in certain positlons of' the knee, and hence this construction while admirably adapted under some conditlons was not equally serviceable in all.

Furthermore, in the noted application, the 'i motor mechanismhad its operative part directlyconnected with the kneeand hence it was. dlicult tot adjust the knee to an exact posltion in compensating for wear, as'the motor connection .prevented such adjustment in a commercial practical way.

The present invention provides a motor mechanism which is so associated with the knee that the full maximum range of travel of the knee for taper adjustment is permitted, while the overhang or projection of l`y free of all direct connection with the knee, and the member carried bythe knee to be engaged by the motor in operation is arranged for convenient. adjustment, to

thereby vary the relation of the knee andl operating part of the motor mechanism. Thus, the kneemay be accurately set in a predetermined position and all wear of parts compensated for in maintainingI this predeterminedset of the knee in a simple and convenient manner. p

In the application referred to, the motor mechanism was arranged for-pneumatic control and the respective motor steps of movement were designed for successive operation. While this is advantageous in handling some j types of logs, it has been found that to conserve power in handling other types of logs the motor mechanism should be capable of being operated selectively with respect to jany desired step of movement without the necessity of operating such motor mechanism through any preceding steps of movement.

Therefore, the present invention contem. plates the provlslon of 4a motor, wherein any particular ste or steps of movement may .selectively rought into: play without in any Way affecting or influencing any preceding steps of movement.

In taper mechanisms as heretofore provided, the step by step movement, whether by a motor or vby the ordinary dog and segment, the taper movementof the knee was in exact accord with the motor movement or with the distance between teeth or notches of the control. Under these conditions, the taper of a log was limited kin the number of possible tape-r movements to the number of different taper steps or of teeth or notches. It is however, important that a greater range of taper be permitted a log than is ordinarily possible, owing to the limited space permitted the taper control mechanism with a motor mechanism having normally spaced steps, or one involving teeth and notches.

In the present invent-ion therefore, it has been found desirable to have the motor steps of movement bear a definite predetermined relation in taper measurement, say for example, one and one-half, four and one-half, seven and one-half, and ten and one-half inches taper measurements. lVith two knees provided with a vmotor mechanism having the successive steps of movement as noted, the taper possibilities of the log can be materially increased over the usual construction. For example, desiring to taper a log with a three inch taper measurement, one of the knees will be adjusted through the motor mechanism to the second' step,- moving the log at that end four and one-half inches, while the other of the knees will be adjusted to the first step, moving the log at that endy one and one-half inches. Thus the effective taper will be the Idifference between the one one one-half ymovement of one knee, and the foury and one-half movement of the other knee, or three inches, and from this cited instance, it will be apparent that with thel steps of the motor mechanism arranged as described, al materially increased variety of taper positions of the log is possible as compared with previous taper mechanisms.

The invention also contemplates what may be termed a reverse motor mechanism, which operating under pressure is effective to return the knee to normal position, or to any position determined by the set of the motor mechanism, and also effective in holding the knee, or rather the member thereof engaged by the motormechanism in contact with the operative end of the motor mechanism under all working conditions` to insure that the movement of the knee by the motor mechanism will be exactly as effective as if directly connected.

In the drawings Figure 1 is'a diagrammatic plan view illus- 'trating the invention applied to a saw mill carriage. f Y

Figure 2 is a side elevation of a knee and head blockwith the invention applied.

Figure 3 is a front end view of the same. Figure 4 is a'central longitudinal section through one of the motors and knee.

Figure 5 is a detail view of la group ofcontrol valves.

Figure 6l is a diagrammatic view of one of the composite cylinders when the pistons are in normal position.

Figure 7 is a diagrammatic view of one of the composite cylinders showing the position of the pistons when the control is actuated to obtain the first taper position.

Figures 8, 9, and 10, are similar views, showing the position of the pistons when the control is actuated to obtain respectively the second, third, and fourth taper positions of the pistons. l

Figure 11 is a diagram illustrating the position of the knees when making a standard taper, or when taper measurements of a different variety from the standard are desired, the light 'dotted lines showing the llog position when making a standard taper,

and the heavy dotted lines representing the taper measurements of a dierent variety from the standard desired.

. Figure 12 is a detail view of the slide for supporting the composite'motor.

' Figure 13 is a detail perspective view showing the adjusting means `between the knee and the motor.

Figure 14 is-a Sectional View, partly in elevation, of a taper arrangement according to the preferred construction designed particularly for a rack-and-pinion set works drive. K

In the drawings, particularly Figures 1 to 18, a saw mill carriage is conventionally indicated at l, on which are mounted head blocks 2, formed with guideways 3, to accommodate screws 4 rotated by gears enclosed in alhousing 5 and operated from the set shaft 6. There may be several knees and headblocks and therefore a description of one will suffice.

The upper surfaces of the side flanges of the head block are formed with guides 7, and a slide 8 of a width equalling that of the head block is formed on the underside with grooves 9v to slidably cooperate with the guides 7, the upper surface at the side edges of the slide having gibs 10. A rib 12 depends from the cent-ral portion of the slide, and is provided with a nut housing 13 to vreceive a nut 14 cooperating with the .screw 4.

An integral cylinder section 17 forming part of the motor mechanism, forms part of the slide 8, this cylinder section exfcnding rearwardly from the slide with respect to the knee and is provided near its rear edge with a flange 18. rl`he head of the cylinder, that is, the end toward the knee, is formed with a central opening 19, being otherwise closed. In alignment with the .llO

cylinder section 17, is a plurality of cylinder sections designated -21 and 22 and fittin on the rear end of the last mentioned cylin ler section is a hea-d 23. Tie bolts 24 extend thru the flanges on the rear cylinder section 22 and the flange 18 on the front cylinder section 17,`the structure as a whole formingja composite 'motor cylinder to receive a plurality of'pistons 25-26-27 and 28. The piston 25 is composed of several disks 29,'with interposed packing, the disks being mounted on the reduced endof a rain rod and locked in position thereon by a nut 31, the forward end of the rod extending through the opening 19.

The pistons 26-27 and 28 are all exe actly alike, except as to length, hence I will describe but one in detail. Each piston is hollow, and in its forward end is a cavity 33, to accommodate the nut 31 which secures the disks forming the preceding piston, while the rear end is flanged and has lbolted to it a pair of disks' 34 with suitable packing therebetween. A bolt extends through the rear end of the piston and is locked in place by a nut 35, which is received in the cavity formed in the forward end of the succeeding piston.l The body portion of the piston is ofv less diameter than the interior' diameter of the cylinder section in which it reciprocates, and its periphery is provided with, a plurality of ribs 36 which fit in correspondingly shaped notches or recesses 37 formed in an inwardly extending flange 38, at the forward end of the cylinder section. YThis flange not only affords means in which to'form the guides 37, but it also acts on one side 4to form an abutment tol limit the rearward movement of the piston in the preceding cylinder section and its o posite side forms an abutment to limit tlie forward movement of the piston in the particular cylinder section in which the piston reciproeates. .As stated, the three pistons are just alike except as to their length. Therearmost cylinder sec?` tion 1s the shortest, and each successive cyl- ,inder section in advance thereof is of relatively increased length, each piston from' the rear to Ythe front being of increasing vlength in accordance with the relative lengths of the cylinders, the piston in ad- Vance however,`being merely a series of discs to permitl a stroke equal to the full length 'of the cylinder section in advance. llVhen the parts are in normal position, or in a state of rest, the proportions are such that the front Walls of the three rear pistons terminate just behindV 'the rear wall of the one.

preceding it, there being justl clearance .enough to allow each piston to come up against .its abutting flange.

The length of the respective cylinder sections and theirl 'cooperating pistons as shown, are such as to bring about a definite and predetermined movement of a knee to make what may be designated standard taper adjustments, the various movements being arranged that two knees may be manipulated to maintain the standard, or such to effect taper; positions, of a different variety of tapenmeasurements, as-will appear later on in this description.

Each knee comprises side walls which are connected at their upper ends by a cross member 40, and at the bottom said walls are connected by a cross member 41, which rides on the uppersurface of the flanges of the head block` and when the knee is in normal position said cross member 41 lies adjacent the front edge of the slide 8, as shown in Fig. 4. The sides of the knee depend below the top of the slide and/the top of the flanges of the head block, and to vthe under side of' thedepending portions are fastened inwardly projecting gibs 42 which engage under the side flanges of the head block and form guideways for the movement'of the knee on the slide and head block. In the bottom of the knee are grooves 43, which receive the flanges 10, on the slide, topreadjustment may be broken up or destroyed vent lateral spreading of the knee, while the v i lto fit snugly the walls of the elongated openings, or shims 47 maybe inserted in the openings to insure the free end of the rain 30 of the motor engaging the bar inthe knee to obtain the desired adjustment.

The bar' projects through the elongated y openings, and fastening bolts 49 extend through reinforcing flanges 50 and the bar to/secure said bar in fixed position. It. is essential that the knee be adjusted on the head block so that the-free end of the ram will be up against the square surface of the bar to receive the impact, when the motor is operated, and to move the knee the exact predetermined distance by the movementy of any one, or any combination of pistons,y to

insure-exactness in the measurement in any tapering operation.v To provide for this contingency, the shims or wedges 4:7- niay be inserted in the elongated openings in the sidesof` the knee, after the bar has been adjusted with reference to the end of the rain', the end securing bolts 49 being inserted and tightened to therebyv hold the knee fixed Y relation to its motor. l

Secured to'the flanges .at the lower sides j of the knee areprojecting bars 53, and their rear ends are connected by a plate 54. While the plate is primarily designed to be used for a mounting for operating mechanism carried by the knee, I also utilize it as a stop to limit the movementof the knee in one direction. The plate 54, which thusunder- .lies the cylinder and is connected to and movable with the knee through the bars 53, is adapted to engage the flange 18 of the cylinder (see Fig. 4)` to serve as a limit stop for the knee. Thus in the event of failure of the connection 54 and 55 between the knee and the composite cylinder, the knee is prevented from being thrown oil the carriage through the inertia imparted by op eration of the pistons when the knee does not meet the log.

' Particular attention is directed to the fact that in the construction described, there is sure is introduced lin lthe'coinposite cylinder, the ram and the knee are driven torwardly to a predetermined.selected taper position, limited in each instance by the flanges 38 in the cylinder1 sections, It is however necessary to provide means for returning the knee to normal position after completion of a tapering operation, and also reduce the shock incident to the action of the ram when driving the knee to a tapering position. Y

In the instance shown I provide a pair of cylinders 54 and pistons 55 mounted each side the knee. Each cylinder is pivoted at 56 to a boss on the side of the cylinder section 7, the rods of the pistons '55 operating in said cylinders being .pivotedv to the knee at 57. These cylinders are disposed so as to equalize the pull on the knees under the action and eii'ect ol a constant supply of fluid pressure introduced through the pipes58.

The constant supply of fluid pressure acts on the pistons as to at all times tend to draw the bar and knee up against the ram. Furthermore, when the motor is actuated to drive the knee, to a tapering position, the knee, by momentum will move slightly beyond the desired predetermined position,

and here again the etiect of the constant pressure in the cylinders 54 comes into play. The shock incident to such momentum is readily absorbedl` and then the knee is promptly restored to the desired position without in any way placing undue shock and strain on the motor. This is only made possible by reason of the'lack of a' positive connection between the knee and motor.

It follows therefore that the construction and arrangement of the parts b`etween the set worksmechanism and the knee is designed to provide such flexibility as to greatly reduce the strain and shock von the parts, at the Sametime the knee is brought to an absolute predetermined position to elfect the desired taper.. The cylindersl 54, may each be provided with any appropriate means for absorbing they shock otthe piston in the reciprocal movement. Thismay be in the form of a restricted inlet and outlet opening for the fluid pressure, in proportion to the area of the cylinder to form a vacuum in the movement of the piston, or springs or other cushion mediums may be used as indicated at 54"x in Fig. 2.

The control means for controlling the movement of the knees will be located convenient to the setter.

In the present instance the control is shown as comprising a bank of valves divided into two groups G0 and v61, there being one group for each knee. Eachjvalve is constructed to cooperate withi an inlet port 63, an exhaust port 64, and an' outlet port 65.-

All the inlet ports in one group communicate with a manifold 66 supplied with luid'pressure. 'The outlet port of each valve in group 60, communicates respectively with ports GT-GSw-Gf) and 70, in Vone of the composite cylinders on knee A, while similar 'communication is, had between theoutlet ports of the valves in the group 31 with corresponding ports in the composite cylinder on the companion knee B.

In the modified form of the-invention shown in Figure 14, the preferred construction is shown as adapted for use in connection with set works which include a rack and pinion for adjusting the knee. Certain mechanical changes are necessary to apply the invention to thistype of Iknee, but the principles of the improvements are maintained. f

In these figures 71 indicates the usual set works rack and pinion connection. Extending from and supported on theknee, is a composite cylinder provided with a foi wardly projecting housing 16a. Mounted to reciprocate in the cylinder sections inthe composite cylinder are pistonsnand pro]ect ing from the foremost piston is a ram 30" which abuts against a rectangular bar 73 mounted in elongated openings 7 4 in the upper end of a lever 75, pivoted between the side lates of the knee and pivotally connccte at its lower end to a link 7 5', which in turn is pivoted to a lug at'7 'on' the rack. The elongated openings 7 4 are provided with shiins or wedges and bolts are employed to fasten the parts together after proper adjustment has been made.

While the fluid pressure arrangement is preferred to return the parts to normal position,.I may employ a. spring 78, for this icov purpose. It is evident thaty under certain conditions and on' certain rigs, a spring arrangement may be employed to`return the parts shown in Figures l to 13 to normal position. and that fiuid pressure may be einployedin connection with the modified forni to return the parts to normal'position. It is to be also understood thatv while I have conventionally illustrated two knees in the drawings. additional knees equipped with the invention may be used if desired.

In the operation of the construction vshown in Figs. 1 to 13, let it be assumed that the parts are in normal'position, as illustrated in Figures 2, .land 6 ;'that is, with the bar 46 ofthe knee up against the end ofthe ram 30, and the pistons in the composite' cylinder in a state of rest, and it is desired to move the knee to the first predetermined selected taper position. Valve e in group is operated to admit fluid pressure to the rear end of cylinder section 22 adjacent the head 23 which ldrives the piston 28 forwardly until itslanged end contacts with the first inter` nal flange 38 which limits its forward predetermined movement, as lshown in the diagram in Figure 7, the knee A lbeing advanced to position a log e' against the knees to make a taper of one and one-half inch as shown in Figure 1l. As the pistons are all in alignment, and in' substantial contact with eachother, when in a state of rest, movement of the` rear piston 28 correspondingly advances all -the pistons in the composite cylinder, and through the medium of the ram 30fand the contact bar 46, the knee is advanced a distance equal to the distance travelled by the actuated piston. In the sudden forward movement of the ram, slight overrun momentum is imparted to the knee, but

l this movement is cushioned by the continuous pressure in .cylinders 54-54, and by means of this pressure in cylinders 54, the

knee is instantly returned to,` or may be said to be substantially held in Contact with the vend of the ram. i Thus in the movement of the pistons, the shock on the knee is abi Cn sorbed.

While rovision is made for a taper movement of te knee or knees, as a result of the operation of the rearmost piston, it 4may he and frequently. is desirable to hold the knees in the rst taper position as their normal position, as thereby, particularly in handling large logs, the pressure behind the rearmost pistons of the knees acts as a buii'er to relieve the blowl and strain incident to the.

logs striking the knees. v

It' consecutive and further predetermined taper movements of the `knee or knees is desired, the successive valves I), c, and d, are operated to' admit 'fluid pressure to the respective cylinder' sections, with the result lthat the pistons 27, 26, and 25, will beadvanced bythe'pressure controlled by therespectivelvalves to advance the knees to the limit of movement permitted by the particular piston or pistons. In this connection, it.

is to 'be understood that, as will later appear, i the respective knee movements, yfollowing 70 operation of the particular' pistons, mayfollow asuccessive movement'of `such pistons throughout the series, whereupon the 'knee taper movement will, for example, be advanced say one and one-half inches, four and one-half inches, seven and one-half inches and ten and one-half inches, `but itis of particular importance in they present application to note that the pistons are capable of'selective movement, that'is, any one piston may' be operated to the exclusion of theothers. Thus as rthe stroke of the iinal piston 25 is, for example, ten and one-half inches, this taper movement of the knee may be secured by progressively operating a`ll of the pistons 854 from the rearmost forward by manipulation of the valves a, b, c, d, in succession, though i'f desired, the ten and one-half inch ktaper movement of the knee 'may` be instantly obtained by operating valve d, and i thereby actuating piston 25 to the exclusion of and without affecting the other pistons.

selective possibility that renders the construction highly important in the saving of time andthe economic use of the pressure fluid.

The construction is such that any one of the desired movements may be selected and made, without disturbing the position of the pistons in rear of the one selected to obtain the predetermined selected position of the knee fora definite taper location. For 1nstance, let itbe assumed that a four and -This is equally true for the taper movement vresulting from any one piston, and it is this 9 tion 17 and the respective piston or pistons moved as shown in Figures 9 and 10.V

' It may here be stated that when the last or an intermediate selection is made, the valves previously operated may be set to exhaust position to retnrnthe previously operated piston 'to normal position, although this is not necessary, it being entirely optional with the operator. If, while the parts are positionedto locate the knee at any of one of the increased taper positionsbeyond the first, for instance a position resulting from actuation'of either of pist-ons 27,126 or 25, and a predetermined position of the knee 49 mains in normal to produce a less taper on the log, say one andone-half inch, is desired valve ar will be opened to admit pressure in therear end of cylinder section 22 adjacent the head 23 and valves b, c and d will b e opened to exhaust,

Vand the continuous pressure in cylinders 54 will return the knee, pistons 27, 26 and 25v being driven rearwardly until piston 27 contactswith the 'piston 28.` This would also `be truefwith other cylinder sections and pist0ns,if a change of position bedesired, so-

tliat any predetermined taper-position of.v the knee maybe obtained, 4it merely requiring manipulation of the proper valves to obtain the result-sought. y

It lfollows from thisdescription of the operation that the operator has a wide range of predetermined selections of Vtaper positions without depending upon the successive movementsI or actuation of the Ypistons in A rear of those to be operated. In'other words,

by the construction-and arrangement shown, an operator may pick out any one of the pistons and obtain a predetermined selected position, without having first to actuate the pistons for producing a less movement of the knee than that desired. y

In practice it is preferable to provide predetermined movements of each knee, equaln ling distances which may be so sub-divided as to provide increased tapering positions by manipulating both knees. Thus, pistons 28 will advance the knees one' and one-half inches; pistons 27 will advance the knee i four and one-half inches;ipistons 26 will 28 in 'one composite cylinder is actuated,`

knee B will be advanced one and one-half inches, and if piston 27 in the v companion composite cylinder is operated and knee A it controls is advanced four and one-halt` inches, the distance between the Vfaces of the' two knees will be three inches, hence a taper positionaccording to this measurement will result, as indicated by heavy dotted lines A11, in -Fi ure 11. With knee B 66 still remaining in t e one and one-half inch position, if piston 26 in the companion composlte cylinder is actuated to bring the knee A to the seven and one-half mchtaper position, or piston 25 in said cylinder is actuated to bring the knee to the ten and one-half inch taper posltion, six and nine inch taper positionsrespectively will result, as shown by the heavy dotted lines o and p in` Figure 11.A Therefore, by the construction described` I am enabled to soimanipulate the pistons as to bring about predetermined selected standard ta er positions of a knee or knees, and by com ining the manipulations ofthe two'V groups of plstons I am able to select taper positions, the Ameasurements produced thereby,\bein ahidivisiongof the standard. In other 'wor s, in lieu of a series of predetermined. selected positions depending on those ollowing the resultant normal action of the pistons, yif advanced distances equalling even inches be desired, I am, by making themovements of the pistons include one and one-half inch measure, enabled to combine the movements of the groups of pistons, and roduce another series of -movements ofdi erent measurements, and4 thusy increase the number of adjustments of the knees for' tapering purposes, -withou't unnecessarily increasing the length ,of the operating means for bringing about'the result.

When a log is thrust on the carriage, the Huid pressure behind the pistons serves to greatly reduce the shock and strain on the parts. This action is greatly augmentedl by the independence between the end of the ram and the'cooperating cross bar, as the flexibility between these 4two parts is such that whenr the knees receive the ,blow of a log, the jar is transmitted to the pistons, and is promptly absorbedby the cushion, and while the log is settling, this cushion acts -immediately to bring the ram back to its exact predetermined position.

In these operations, the major portion of the knee operates on andis supported on the slides 8, while the front end of the knee operates on and is supported on the head blocks. This aii'ords'strength vand rigidity to the knee structure andyet the knee and slide as a unit can be set by the usual setting mechanism wholly independent of the pistons. Furthermore it will be seen that the construction is such that the sides ot the knee are held together at the bottom by the flanges, and the lower cross member pri-- vents lateral spreading, while upward movement of the knee and slide is prevented by the gibs 42. Then again the construction and arrangement of the-grooves and gibs between the slide and block are such that the slide is held against lateral movement, and yet an effective guide is formed for the slide vornthe head block when using thc usual setting mechanism.

-In the operation of the modified form ot the-invention shown in Figure 14,the conpreviously described, but in lieu of the ram vacting directly on the knee it acts'on the Atrol 'valves are operated in the same way as v and the link, the-knee is adjusted on the head block for tapering purposes. The springin this instance serves as a knee return motive power, and additionally to mainf selected piston, by operating 'directly by.

admitted pressure, lis-the only one to dito la'corresponding tapering position.

termined tapering lrectlyinlluence the knee;I That is' to Say,

the pistons are'fnot, strictly speaking consecutively advanced by the piston in its rear contacting with it, as outlined iinthe` described modified form.l Thus a substantial predetermined selection of piston movement is secured without depending onthe rear neighboring piston moving the one. ahead of it.

In the preferred form, it will be seen that theeavity inthe knee affords a seat for the reception of the'forward end ot' the com'- posite cylinder, by meansof which the overhang of the cylinder is materially reduced. Otherwise, it themovements of the pistons V in any one cylinder were arranged to produce all the taper positins herein described` the length of the cylinder would be such that it would overhang the carriage to an extent as to make the construction impractical in certain types of saw mill carriages.

lVhat I claim isz- 1. In a saw mill carriage, a head-block, a knee movable thereon for taper purposes, a cylinder carried by and movable with the knee above the head block, a series of pistons operating in the cylinder, said pistons being aligned in the cylinder and operating inthe same direction to impart respectively predetermined taper movements to the knee, and means for selectively operating said pistons.

2. In a saw mill' carriage, a head block, a knee movable thereon for taper purposes, a motor mechanism including a cylinder carried by and movable with the knee above the head block, a-series of wholly independent pistons arran ed in the cylinder and each having a pre etermined limit of movement, said pistons being arranged in alignment and operative in thesame direction to exert a moving'pressure on the knee, and means for selectively operating said pistons.

3. IIn mechanism for setting and tapering alog on a saw mill carriage, a knee, set

works, a motor associated with the knee, saidmotor comprising a plurality of aligned pistons arranged to advance the knee to predepable of selection or acting on a predetermined piston or pistonsto advance thevknee N l ositions, and means ca-` elements to position the knee forapredetermined selected tapering position, and means independentof the control means for returning the elements and the knee ,to normal position. f y

. 5.,.In n'lechanisnrfor settingand tapering `a log ona saw mill carriage, a knee, set

works, a motor associated with the knee,

said motor comprising a plurality ot alignedpistons, one of which engages only the,V knee, and control means vcapable `of selectively actuating any one of o1 combinations of said y pistons to advance. theknee to a corresponding predetermined position, and means independentoiI the *controlfor returning the knee and piston orpistonstonormal position. g

6. In mechanism :tor setting and tapering a log ona saw mill carriage, a knee, a head block,l a slide on vthe head block, a motor carried by the slide, said motor comprising a plurality et aligned pistons, one et which is provided With a ram4 adapted to -extend beyond themotor and abut the knee, means to maintain abutting Contact ot the ram with the knee, and means tor controlling the movement of the pistons to advance the lmee to a predetermined position.

7. A tapering mechanism for the knee of a saw mill carriage, comprising a motor carried by and ln'iovable with the knee and including aseries of aligned pistons, each with a predetermined limit ot movement, and means to cause the movement of any selected piston to correspondingly move uthe knee for taper purposes.

8. In mechanism for setting' and tapering a log on a saw mill carriage, a knee, a head block, a motor between the knee and head block,'said motor having a ram at one end to abut 'the knee, means capable-.of being actuated to advance the ram `to predetermined selected positions to correspondingly position the knee, and means for maintaining the `almtting relation of the ram and knee.

9. In log taperingmechanism Jr'or saw mill carriages, including a knee, a head block, a motor for operating the` knee relative to thc head block, said motor comprising a seriesv of l'nstonsarranged 1n valignment andeach- Vhaving a limited range of travel, meansv Wherebythe linear movement ofthe-'pistons or any selected piston may be. communicated in like distance to the knee', and fluid ressure control means capable of selectively'.`

i loi) operating any one of said pistons to impart to the knee a movement resultant from the travel of the selected piston or pistons.

10.- A log tapering mechanism for saw millv carriages, having av head block. and av knee movable relative thereto, a motor, in-

cluding ya cylinder carried by. the knee and.A

v pistons operative within the cylinder, said pistons being free of connection with the knee but-capable of exerting pressure thereon in the movement ofthe -pistons or 'any of them in .one direction, means for operating the pistons, and means for exerting a pressure on the 4,knee in opposition to the piston movement, whereby to maintain operative engagement ybetween the pistons and knee in all operative positions oi the pistons( 11'.A In combination with a knee and supporting headblock of a' saw -mill carriage, of a motor mechanism. for the knee comprising a ,cylinder carried by the knee, a

series of .pistons arrangedwithin and. operative in. alignment inthe cylinder, a fluid pressure means, and, mechanism for 'selectively controllingthe fluid pressure means to 'therebypoperate any particular piston or pistons, and means whereby the linear movement of the selected piston or pistons may be communicated in like distance to the knee. d

12. In a saw mill carriage'having head blocks, kneesfmovable relative thereto, motor mechanism associated with each knee and including a series of pistons aligned inacylinder and operative in the same direction to move the knee relative to the head-block, the movement of the successive pistons in a cylinder beingof relatively increasing distances from the rearmost toward the foremost of such pistons, means for operating any one ofthe pistons, and means for moving each of the knees in opposition to the piston movement` thereof to an extent permitted by the selected 'final active piston of the particular motor, whereby the knees colv lectively may be moved throughout a .taper range aggregating the movement of the pistons ineither `or both motors or to a range indicated byAthe difference in movement of the non-similar pistons of the respective motors.

13. In'knee tapering` mechanism for saw mill carriages having a head block, a knee Cil and a knee movable relative thereto, motor means operative to impart to the knee aV range of travel made up 4of a series of in-' herently limited movements, and `means for controlling the application of said'rst mentioned means to select the particular limited. movement to which theV knee is to be sub-,i

jected.

15. Mechanism for tapering a log on a saw mill carria @including a head block, 7.5=

a knee, a mem er interposed between the knee and head block, with such member movable relativeto the knee and the knee movable relative to such member, -and a motor for tapering the knee, said motor in-A y l cluding a cylinder carried by the member with the knee movable relative to the cylinder in taper movement, and a plurality of pistons operating within the cylinder to taper the kneel to different distances, said pistons directly` operating the knee in taper movement. v y

16. Mechanism.. for tapering alo on a. saw mill carriage including a hea block and a lknee movable relative thereto, of a motor for tapering the knee, said motor including a. cylinder with which the knee iS relatively movable, av plurality of'pistons.v

aligned in the cylinder and operable in the same direction to respectively provide a plurality of predetermined taper movements .for the knee, a fluid pressure meansv for istons, and means for con- ,y

operating said trolling said fluid pressure means to permit selective independentvoperation of an one of said pistons or substantially simu tane- Y ous operation thereof at will.

17. Mechanism for tapering a log on a 'saw mill carriage, including a head block and a knee movable relative thereto, motor meansfor taper operation of the knee, said motor means comprising a cylinder and a plurality of aligned independent pistons arranged in said cylinder, each of said pistons having a limited stroke, fluid pressure.

means, and'valve mechanism for controlling said fluid pressure means to selectively operate any one of said pistons or to operate allor any number of said pistons in a, substantially simultaneous fluid pressure ad-v mission to the pistons.

18. In mechanism for tapering a log on a saw mill carriage, a knee, a plural aligned lpiston motor wherein leach, piston has an inherently limited taper producing movement, means for operating the pistons, and

yielding means for limiting the vmovement of the knee under the inertia imparted thereto in the piston operation.

i 19. In a saw mill carriage, a head block, a knee movable thereon-for taper purposes, a cylinder, a series of pistons aligned-in the cylinder and'selecti-vely yoperable to impart respectively predetermined taper movements and duid pressure l lected jf @wie means for operating the .selected piston, said fluid pnssure means actin p stonras a buifer pact on the knee.

20. A sawmill car-ria kneev movable thereon or .taper purposes,` aseries of aligned 'elements ada ted when moved to impart respectivelypre etermined movements to theknee,1neanswhereby an or opposing imoperating-pressure may be introduced for movable for taper cludng` a series .of a 'gned elements wholly the selective operation of any one of said elements to thereby operate suolil elementfor knee-taper inoveme'nt and simultaneously provide a lbufferv for the-knee under log impact. y e

21. A saw mill carriage having 'a knee urposes', a motor inindependentof the knee andy each capable of. individually imparting a .taper move-f. 4ment tothe knee, pressure means capable of selectivelyv operating any fone of said* e1 `ements,`aj,'nd means for .urging the f. knee in opposition to. the 'movement of the elements-to maintain operative engaenent between the ,elementsandkneej at a times.y

alo

22. Ina saw inill carriage, a. knee'movable connection wi iiuidx Lressure 'to im rt af taper movement sure means and yielding serving 'as opposing bu'iers." or theknee.

' 'movable -lioriaontallygin animi, including anj element to directly revthrough the se#4 e, a had block, fi'

s,' amotorfree of direct the l v and jacting under ee,- and y-iel ing pressure means acting to hold the knee in position to be responsive to motor movement, said uid jpres'` ressure means works, and a plural pistonmotor wherein eiwh piston is capable of imparting a predetermined advanced movement to said element, andmeans whereby a piston or pis'- tons. may -be operated to advance said element and simultaneously provide a buffer for the movement of `the element under logimlact. 24. a logtaperindg mechanism for saw mill carriages, inclu ing a knee formed y5o 1 with acavity and la transverse `bai' extending across the cavity, a head block, a motor for operating the knee relative to' the head block. said motor comprisingv a. cylinder and a series of'pistons arran ed in align-f ment and each iston having a. ited range of travel, the orwardend ofthe cylinder being housed in the cavity .when the istons are in normal position means inc uding element extending. from the foremost iston' and' cooperating ,with .the ;.transverse f y ar, whereby the linear movement Vo f'the pis-.jt tons or an selected piston may becommuni- `1 cated in distance to the knee, and means 'ff capable"offselectivelyV operatin y any; one of said pistons to impart tothe eea movef'f. ment.- resu1tant'from the 4travekof the selecv ed piston or pistons* .1 25. In a saw mill carriage,a' h ead block, a. .1 .knee vmovable thereon'A for tapernlpurposea .vo acylinder aqseries oi pistonsA gned 'in if the cylin er and lselectively. 'operable to y impart respectively predetermined. taper; movements to the knee, fluid pressure meansfor operatin the selected piston, and x'iieansfli.l .i between theglmeeand cylinder toy limit the 

